FreeSans horizontal misalignment in PDF, SVG, PS backends #912

As noted in issue #903, the FreeSans '1' doesn't align properly on both the x and y axes when saved to .pdf, but does align reasonably when displayed and when saved to .png:

plot(np.arange(10))
gcf().savefig('freesans_example.png')
gcf().savefig('freesans_example.pdf')
gcf().savefig('freesans_example.svg')

Here are the resulting files:

http://devio.us/~mspacek/freesans_example.png
http://devio.us/~mspacek/freesans_example.pdf
http://devio.us/~mspacek/freesans_example.svg

It's too far to the right on both the x and y axes in both the .pdf and the .svg. This isn't really apparent in the .png (although still slightly off on the y axis), and doesn't happen with the default sans-serif font:

plot(np.arange(10))
gcf().savefig('sans-serif_example.png')
gcf().savefig('sans-serif_example.pdf')
gcf().savefig('sans-serif_example.svg')

Here are the resulting files:

http://devio.us/~mspacek/sans-serif_example.png
http://devio.us/~mspacek/sans-serif_example.pdf
http://devio.us/~mspacek/sans-serif_example.svg

Changing pdf.fonttype to 42 doesn't seem to have an effect.

Note all 6 of these files were generated with @jkseppan's fix for TrueType to Type-3 font conversion in #905, so the 0's and 8's look correct in the .pdf.